#include <iostream>

class DifferenceTable{
    private:
        int head;
        int tail;
        double value;
    public:
        DifferenceTable(int h, int t, double v):head(h), tail(t), value(v){}
        DifferenceTable():head(0), tail(0), value(0){}
        ~DifferenceTable(){}
        int get_head(){return head;}
        int get_tail(){return tail;}
        double get_value(){return value;}
};